I recently added a Vega Frontier Edition to a 15" 2017 MacBookPro. I'm disappointed to see that Neat video performance is actually a little worse with either the internal or external GPU engaged compared to 7 CPU cores only. Am I possibly doing something wrong? (The eGPU is on its own dedicated Thunderbolt 3 channel, and it shows notable performance improvements to other operations in both Resolve and FCPX.)

It is possible that the problem is in the Mac versions of the GPU drivers that are known to run modern AMD GPUs slower than the corresponding GPU drivers running under Windows. For example, please compare the results from Radeon RX Vega 64 under Windows and in MacOS posted in our blog.

Perhaps the CPU is winning on your machine for the same reason as well. If you can make a comparative test by running for example NeatBench in Windows on the same machine, then it could help to verify this hypothesis.

Regarding other applications, such Resolve and FCPX, different tools place different types of load on the GPU itself and on the connection between the main system and GPU, so it is normal to see different relative speed up/down when running different tools. Neat Video requires both high speed connection and high speed computation on the side of GPU. Perhaps one of those is lacking for some reason. The GPU drivers is one possibility.